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Within a few-cycle laser, the generation of MHz isolated extreme ultraviolet (XUV) attosecond pulses via nanoplasmonic field enhancement in silver nanostructures is theoretically investigated. Numerical techniques are employed to optimize nanoantennas and attain plasmonic field enhancement factors up to 270. In a volume of 15 × 15 × 30 nm-3 in the nanoantenna, the intensity could be enhanced to 1014 W cm-2 for high harmonic generation (HHG). Optimal conditions for the production of MHz isolated attosecond pulses of 140 attosecond duration via HHG have been identified. These findings open up the possibility for the development of a compact source of ultrashort XUV pulses with MHz repetition rates. Moreover, asymmetric cross HHG is proposed to control the polarizations, select the wavelengths by varying the ratio of silver nanoantennas and generate XUV pulses in both polarized directions. [ABSTRACT FROM AUTHOR]

Objective To observe the changes of Han male pubic symphysis surface morphology with different age in Yunnan province, analyze the correlation between pubic symphysis surface morphology and age, and establish an equation for inferring age. Methods We collected 85 Yunnan Han male pubic specimens in daily work, their ages between 17-50 years, and had exact records about ages (specimens of all lesions and removed without damage). We selected six morphological changes in the project to observe and develop appropriate assessment criteria, based on the standard morphological changes on the surface of the pubic symphysis to score, and then usd multiple linear regression method for processing the data obtained, finally, established an equation for inferring age according to Yunnan male pubic symphysis surface morphology. Results With the above method, we established the equation for inferring age according to Yunnan male pubic symphysis surface morphology: = 15.884 + 1.466 X1 + 1.777 X2 + 2.040 X4 + 1.504 X5 + 3.006 X6. Conclusion The equation we established is more better than before in practical applications. [ABSTRACT FROM AUTHOR]

We propose a method for generating double-ring-shaped vector beams. A step phase introduced by a spatial light modulator (SLM) first makes the incident laser beam have a nodal cycle. This phase is dynamic in nature because it depends on the optical length. Then a Pancharatnam–Berry phase (PBP) optical element is used to manipulate the local polarization of the optical field by modulating the geometric phase. The experimental results show that this scheme can effectively create double-ring-shaped vector beams. It provides much greater flexibility to manipulate the phase and polarization by simultaneously modulating the dynamic and the geometric phases. [ABSTRACT FROM AUTHOR]

An all optical method is demonstrated for measuring the carrier-envelope phase (CEP) of few-cycle laser pulses. It is found that, in the few-cycle regime, the high harmonic spectrum generated from asymmetric molecules shows several half-cycle cutoffs that change their positions as the CEP varies. Such half-cycle cutoffs represent the fingerprint of different quantum trajectories and the waveform of the driving pulse. In this case, the CEP can be accurately measured from the half-cycle cutoffs. [ABSTRACT FROM AUTHOR]